1. Field of the Invention
This invention relates to a warmth keeping method for a copying machine, and more particularly to a method for keeping the entire machine installed in a cold place at a constant temperature during the period while the machine is left inoperative.
2. Description of the Prior Art
In a copying machine of the type in which the various copying steps such as charging, exposure and development are accomplished on a sensitive medium having a photoconductive material, the quality and properties of the sensitive medium, corona discharge and developer are the important elements for obtaining a high-quality image. These elements have strong temperature dependency, and in many cases, it is hard to obtain images of good quality constantly, particularly when the ambient temperature is low. This has close relation to the mobility of the light-excited carrier and other like factors, but as such matters have no direct bearing on the import of the present invention, no discussion on their physical meaning is given here.
The copying machine is usually adjusted to operate most efficiently at room temperature, that is, at a temperature of from 20.degree. to 25.degree.C. To a cold district, the room temperature of an office at night time in winter (with the air-heater being switched off) may drop to around -10.degree.C, so that when the cold machine is started in the morning, it takes a considerably long time before the machine temperature is raised up to the same level as room temperature even if the room is warmed by the air-heater, and hence no good-quality images can be obtained at the beginning. As a means for keeping warmth in the inside of the machine when the machine is left inoperative at night time, it has been the general practice to insert a heating element (such as a nicrome wire heater) with a capacity of from several to several ten watts into the machine to keep the intra-machine temperature at a certain level.